The essential components for detergent formulations, used in washing of fabrics consist of a detergent compound, also called the detergent surfactant, and a detergent builder. Additionally, there may be present a number of other constituents, most notably the sodium silicates to provide buffering, anti-redeposition agents, softeners, fluorescent dyes, enzymes, bleaches, chlorine releasing agents and perfumes, etc. The balance of the formulation is generally a filler such as sodium sulfate and water. Thus, standard basic detergent formulations may be described by the following major components and percentages:
______________________________________ PERCENTAGES POWDERED LIQUID COMPONENT PRODUCTS PRODUCTS ______________________________________ surfactant 10 - 20 8 - 12 builder 30 - 50 15 - 30 sodium silicate 5 - 10 5 - 10 sodium sulfate 5 - 45 0 - 2 water 10 - 15 40 - 60 hydrotrope and/or other organic 0 - 5 0 - 10 detergent adjuncts ______________________________________
The detergent surfactant which can be an anionic, nonionic, zwitterionic, or ampholytic compound or can be a mixture thereof, is most frequently an anionic such as sodium linear secondary alkyl (C.sub.10 -C.sub.15) benzene sulfonate or a nonionic such as an adduct of 11 moles of ethylene oxide with 1 mole of a linear C.sub.14 -C.sub.15 alcohol. In powdered products, nonionic detergent surfactants are generally used at the lower end of the range, e.g., around 10 to 13% while the remainder of the surfactants are used in the 15 to 20% range. In liquid products, all of the surfactant compounds are usually used at relatively lower levels, around 8 to 12%.
Typical builders for detergent formulations are the polyphosphates such as pentasodium tripolyphosphate and tetrapotassium pyrophosphate although considerable effort has been made of late, by those skilled in the art, to find replacements for these compounds because of the alleged effect phosphates have on eutrophication of certain bodies of water. While there are many factors which can be considered determinative of whether or not a compound is suitable as a detergent builder, such as the relative ability to sequester calcium and magnesium ions from solution, the crucial question always is -- will it clean clothes under standard, in-home conditions. All too often compounds which appear to be efficacious in the laboratory fail to perform during in-home tests.
Careful analysis to determine causes for these poor responses has shown that no matter how explicit the use level recommendations for a detergent composition, the housewife frequently under uses the product, sometimes by as much as one-half. By way of example, most detergent compositions call for an optimum concentration of about 0.2 percent, i.e., so many cups per wash load for that type and size of washing machine to give a detergent concentration in the wash water of 0.2 percent. Practically, however, a significant percentage of housewives either do not take the trouble to measure out the required quantity and will under-estimate what is required or, will, in an attempt to save money, use one-half to three-quarters of the recommended level.
Under-use of this caliber does not represent a serious problem with detergent compositions using phosphate compounds since they are such excellent builders that the slight loss in detergency is usually not noticed. However, none of the replacements for phosphates developed to date has the building efficiency of phosphates even under the most ideal conditions. Thus, a compound which is 90 to 95 percent as efficient as phosphate when properly used drops to 85 to 80 percent and even lower efficiency if the formulation is under used. As a result a compound which was considered as a feasible alternative to phosphates becomes unacceptable.